The impact of social media, such as Facebook in various fields including education is undeniable. The main objective of this study is to examine the effect of the interaction between students' learning styles and learning approaches on their achievements in the chemistry subject using the Problem-Based Learning (PBL) method through Facebook. The sample of this study consisted of 120 MARA College students, who were randomly selected to undergo PBL treatment via Facebook for nine weeks. This quantitative study used the 4×2 factorial experimental design. The main variables were the students' learning styles (visual, aural, reading-writing, and kinaesthetic) and learning approaches (surface learning and deep learning) as well as the interaction between both on their achievement in the final examination for chemistry subject. The two-Way ANOVA test results showed that the main effect of students' learning styles on their achievement in chemistry was significant across students' learning approach using PBL via Facebook. Furthermore, the Post-Hoc test had found that the mean for the reading-writing style of learning was significantly better than for other learning styles. Similarly, the main effect of learning approaches was also found to be significant across students' learning styles. It was found that the mean value for the deep learning approach was significantly higher than the mean value for the surface learning approach using the PBL method via Facebook. However, the effect of the interaction between these two independent variables (learning styles and learning approaches) on students' achievement was not significant.